4.14-stable review patch. If anyone has any objections, please let me know.
------------------ From: Andy Lutomirski <[email protected]> commit f7cfbee91559ca7e3e961a00ffac921208a115ad upstream. Share the cpu entry area so the user space and kernel space page tables have the same P4D page. Signed-off-by: Andy Lutomirski <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Cc: Boris Ostrovsky <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Dave Hansen <[email protected]> Cc: David Laight <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: Eduardo Valentin <[email protected]> Cc: Greg KH <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Juergen Gross <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Will Deacon <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/mm/pti.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -265,6 +265,29 @@ pti_clone_pmds(unsigned long start, unsi } /* + * Clone a single p4d (i.e. a top-level entry on 4-level systems and a + * next-level entry on 5-level systems. + */ +static void __init pti_clone_p4d(unsigned long addr) +{ + p4d_t *kernel_p4d, *user_p4d; + pgd_t *kernel_pgd; + + user_p4d = pti_user_pagetable_walk_p4d(addr); + kernel_pgd = pgd_offset_k(addr); + kernel_p4d = p4d_offset(kernel_pgd, addr); + *user_p4d = *kernel_p4d; +} + +/* + * Clone the CPU_ENTRY_AREA into the user space visible page table. + */ +static void __init pti_clone_user_shared(void) +{ + pti_clone_p4d(CPU_ENTRY_AREA_BASE); +} + +/* * Initialize kernel page table isolation */ void __init pti_init(void) @@ -273,4 +296,6 @@ void __init pti_init(void) return; pr_info("enabled\n"); + + pti_clone_user_shared(); }
